I have the same problem. This is what I get when I start the program from the terminal:

sonmez@sonmez-desktop:~$ skencil
*** glibc detected *** /usr/bin/python: free(): invalid pointer: 0xb7e07e78 ***
======= Backtrace: =========
/lib/tls/i686/cmov/libc.so.6[0xb7eaf7cd]
/lib/tls/i686/cmov/libc.so.6(cfree+0x90)[0xb7eb2e30]
/usr/lib/skencil/Sketch/../Lib/paxmodule.so[0xb7b36984]
/usr/bin/python[0x8110e6a]
/usr/bin/python(PyEval_EvalFrameEx+0x6150)[0x80c8f80]
/usr/bin/python(PyEval_EvalFrameEx+0x6135)[0x80c8f65]
/usr/bin/python(PyEval_EvalFrameEx+0x6135)[0x80c8f65]
/usr/bin/python(PyEval_EvalCodeEx+0x775)[0x80c9d65]
/usr/bin/python(PyEval_EvalFrameEx+0x53f9)[0x80c8229]
/usr/bin/python(PyEval_EvalCodeEx+0x775)[0x80c9d65]
/usr/bin/python[0x8112096]
/usr/bin/python(PyObject_Call+0x27)[0x805c787]
/usr/bin/python[0x80628e4]
/usr/bin/python(PyObject_Call+0x27)[0x805c787]
/usr/bin/python(PyEval_EvalFrameEx+0x2031)[0x80c4e61]
/usr/bin/python(PyEval_EvalCodeEx+0x775)[0x80c9d65]
/usr/bin/python[0x8112096]
/usr/bin/python(PyObject_Call+0x27)[0x805c787]
/usr/bin/python[0x80628e4]
/usr/bin/python(PyObject_Call+0x27)[0x805c787]
/usr/bin/python(PyEval_CallObjectWithKeywords+0x6c)[0x80c1f7c]
/usr/bin/python(PyInstance_New+0x71)[0x8066031]
/usr/bin/python(PyObject_Call+0x27)[0x805c787]
/usr/bin/python(PyEval_EvalFrameEx+0x2031)[0x80c4e61]
/usr/bin/python(PyEval_EvalFrameEx+0x6135)[0x80c8f65]
/usr/bin/python(PyEval_EvalCodeEx+0x775)[0x80c9d65]
/usr/bin/python(PyEval_EvalCode+0x57)[0x80c9dd7]
/usr/bin/python(PyRun_FileExFlags+0xf8)[0x80e91d8]
/usr/bin/python(PyRun_SimpleFileExFlags+0x187)[0x80e9467]
/usr/bin/python(Py_Main+0x9c0)[0x8059330]
/usr/bin/python(main+0x22)[0x8058862]
/lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xdc)[0xb7e5debc]
/usr/bin/python[0x80587b1]
======= Memory map: ========
08048000-0813f000 r-xp 00000000 08:01 2632922    /usr/bin/python2.5
0813f000-08164000 rw-p 000f6000 08:01 2632922    /usr/bin/python2.5
08164000-08496000 rw-p 08164000 00:00 0          [heap]
b6e00000-b6e21000 rw-p b6e00000 00:00 0 
b6e21000-b6f00000 ---p b6e21000 00:00 0 
b6fb2000-b6fbd000 r-xp 00000000 08:01 560029     /lib/libgcc_s.so.1
b6fbd000-b6fbe000 rw-p 0000a000 08:01 560029     /lib/libgcc_s.so.1
b6fce000-b6fd0000 r-xp 00000000 08:01 2814662    /usr/lib/python2.5/lib-dynload/fcntl.so
b6fd0000-b6fd1000 rw-p 00002000 08:01 2814662    /usr/lib/python2.5/lib-dynload/fcntl.so
b6fd1000-b6fd3000 r-xp 00000000 08:01 2814618    /usr/lib/python2.5/lib-dynload/_random.so
b6fd3000-b6fd4000 rw-p 00002000 08:01 2814618    /usr/lib/python2.5/lib-dynload/_random.so
b6fd4000-b6fd8000 r-xp 00000000 08:01 2814661    /usr/lib/python2.5/lib-dynload/binascii.so
b6fd8000-b6fd9000 rw-p 00003000 08:01 2814661    /usr/lib/python2.5/lib-dynload/binascii.so
b6fd9000-b6fda000 ---p b6fd9000 00:00 0 
b6fda000-b77da000 rw-p b6fda000 00:00 0 
b77da000-b77e0000 r-xp 00000000 08:01 671959     /usr/lib/skencil/Lib/paxtkinter.so
b77e0000-b77e1000 rw-p 00005000 08:01 671959     /usr/lib/skencil/Lib/paxtkinter.so
b77e1000-b77e4000 r-xp 00000000 08:01 671706     /usr/lib/skencil/Sketch/Modules/pstokenize.so
b77e4000-b77e5000 rw-p 00002000 08:01 671706     /usr/lib/skencil/Sketch/Modules/pstokenize.so
b77e5000-b77e6000 r-xp 00000000 08:01 671704     /usr/lib/skencil/Sketch/Modules/_type1module.so
b77e6000-b77e7000 rw-p 00000000 08:01 671704     /usr/lib/skencil/Sketch/Modules/_type1module.so
b77e7000-b77ed000 r-xp 00000000 08:01 671962     /usr/lib/skencil/Lib/streamfilter.so
b77ed000-b77ee000 rw-p 00005000 08:01 671962     /usr/lib/skencil/Lib/streamfilter.so
b77ee000-b782f000 rw-p b77ee000 00:00 0 
b782f000-b7832000 r-xp 00000000 08:01 2814675    /usr/lib/python2.5/lib-dynload/time.so
b7832000-b7834000 rw-p 00002000 08:01 2814675    /usr/lib/python2.5/lib-dynload/time.so
b7834000-b7917000 rw-p b7834000 00:00 0 
b7917000-b792a000 r-xp 00000000 08:01 2634126    /usr/lib/libz.so.1.2.3
b792a000-b792b000 rw-p 00012000 08:01 2634126    /usr/lib/libz.so.1.2.3
b792b000-b7949000 r-xp 00000000 08:01 2634409    /usr/lib/libjpeg.so.62.0.0
b7949000-b794a000 rw-p 0001d000 08:01 2634409    /usr/lib/libjpeg.so.62.0.0
b794a000-b797c000 r-xp 00000000 08:01 540198     /usr/lib/python2.5/site-packages/PIL/_imaging.so
b797c000-b797f000 rw-p 00032000 08:01 540198     /usr/lib/python2.5/site-packages/PIL/_imaging.so
b797f000-b7987000 rw-p b797f000 00:00 0 
b7987000-b7994000 r-xp 00000000 08:01 2633597    /usr/lib/libXext.so.6.4.0
b7994000-b7995000 rw-p 0000d000 08:01 2633597    /usr/lib/libXext.so.6.4.0
b7995000-b7a44000 r-xp 00000000 08:01 2633822    /usr/lib/libtcl8.4.so.0
b7a44000-b7a4a000 rw-p 000af000 08:01 2633822    /usr/lib/libtcl8.4.so.0
b7a4a000-b7b1d000 r-xp 00000000 08:01 2634997    /usr/lib/libtk8.4.so.0
b7b1d000-b7b29000 rw-p 000d3000 08:01 2634997    /usr/lib/libtk8.4.so.0
b7b29000-b7b3a000 r-xp 00000000 08:01 671958     /usr/lib/skencil/Lib/paxmodule.so
b7b3a000-b7b3c000 rw-p 00010000 08:01 671958     /usr/lib/skencil/Lib/paxmodule.so
b7b3c000-b7b40000 r-xp 00000000 08:01 2633289    /usr/lib/libXdmcp.so.6.0.0
b7b40000-b7b41000 rw-p 00003000 08:01 2633289    /usr/lib/libXdmcp.so.6.0.0
b7b41000-b7b43000 r-xp 00000000 08:01 2633037    /usr/lib/libXau.so.6.0.0
b7b43000-b7b44000 rw-p 00001000 08:01 2633037    /usr/lib/libXau.so.6.0.0
b7b44000-b7c31000 r-xp 00000000 08:01 2633217    /usr/lib/libX11.so.6.2.0
b7c31000-b7c35000 rw-p 000ed000 08:01 2633217    /usr/lib/libX11.so.6.2.0
b7c35000-b7c38000 r-xp 00000000 08:01 2814643    /usr/lib/python2.5/lib-dynload/cStringIO.so
b7c38000-b7c39000 rw-p 00003000 08:01 2814643    /usr/lib/python2.5/lib-dynload/cStringIO.so
b7c39000-b7c3c000 r-xp 00000000 08:01 2814668    /usr/lib/python2.5/lib-dynload/math.so
b7c3c000-b7c3d000 rw-p 00002000 08:01 2814668    /usr/lib/python2.5/lib-dynload/math.so
b7c3d000-b7c43000 r-xp 00000000 08:01 2814660    /usr/lib/python2.5/lib-dynload/array.so
b7c43000-b7c45000 rw-p 00006000 08:01 2814660    /usr/lib/python2.5/lib-dynload/array.so
b7c45000-b7c5c000 r-xp 00000000 08:01 671703     /usr/lib/skencil/Sketch/Modules/_sketchmodule.so
b7c5c000-b7c5e000 rw-p 00016000 08:01 671703     /usr/lib/skencil/Sketch/Modules/_sketchmodule.so
b7c5e000-b7c5f000 r--p 00000000 08:01 2699269    /usr/lib/locale/en_US.utf8/LC_NUMERIC
b7c5f000-b7c60000 r--p 00000000 08:01 2698239    /usr/lib/locale/en_US.utf8/LC_TIME
b7c60000-b7d37000 r--p 00000000 08:01 2699263    /usr/lib/locale/en_US.utf8/LC_COLLATE
b7d37000-b7d38000 r--p 00000000 08:01 2698240    /usr/lib/locale/en_US.utf8/LC_MONETARY
b7d38000-b7d39000 r--p 00000000 08:01 2716544    /usr/lib/locale/en_US.utf8/LC_MESSAGES/SYS_LC_MESSAGES
b7d39000-b7d3a000 r--p 00000000 08:01 2699380    /usr/lib/locale/en_US.utf8/LC_PAPER
b7d3a000-b7d3b000 r--p 00000000 08:01 2698241    /usr/lib/locale/en_US.utf8/LC_NAME
b7d3b000-b7d3c000 r--p 00000000 08:01 2698242    /usr/lib/locale/en_US.utf8/LC_ADDRESS
b7d3c000-b7d7d000 rw-p b7d3c000 00:00 0 
b7d7d000-b7d81000 r-xp 00000000 08:01 2814673    /usr/lib/python2.5/lib-dynload/strop.so
b7d81000-b7d83000 rw-p 00003000 08:01 2814673    /usr/lib/python2.5/lib-dynload/strop.so
b7d83000-b7d8a000 r--s 00000000 08:01 2665999    /usr/lib/gconv/gconv-modules.cache
b7d8a000-b7dc5000 r--p 00000000 08:01 2698366    /usr/lib/locale/en_US.utf8/LC_CTYPE
b7dc5000-b7e48000 rw-p b7dc5000 00:00 0 
b7e48000-b7f83000 r-xp 00000000 08:01 589160     /lib/tls/i686/cmov/libc-2.5.so
b7f83000-b7f84000 r--p 0013b000 08:01 589160     /lib/tls/i686/cmov/libc-2.5.so
b7f84000-b7f86000 rw-p 0013c000 08:01 589160     /lib/tls/i686/cmov/libc-2.5.so
b7f86000-b7f89000 rw-p b7f86000 00:00 0 
b7f89000-b7fae000 r-xp 00000000 08:01 589164     /lib/tls/i686/cmov/libm-2.5.so
b7fae000-b7fb0000 rw-p 00024000 08:01 589164     /lib/tls/i686/cmov/libm-2.5.so
b7fb0000-b7fb2000 r-xp 00000000 08:01 589660     /lib/tls/i686/cmov/libutil-2.5.so
b7fb2000-b7fb4000 rw-p 00001000 08:01 589660     /lib/tls/i686/cmov/libutil-2.5.so
b7fb4000-b7fb5000 rw-p b7fb4000 00:00 0 
b7fb5000-b7fb7000 r-xp 00000000 08:01 589163     /lib/tls/i686/cmov/libdl-2.5.so
b7fb7000-b7fb9000 rw-p 00001000 08:01 589163     /lib/tls/i686/cmov/libdl-2.5.so
b7fb9000-b7fcc000 r-xp 00000000 08:01 589652     /lib/tls/i686/cmov/libpthread-2.5.so
b7fcc000-b7fce000 rw-p 00013000 08:01 589652     /lib/tls/i686/cmov/libpthread-2.5.so
b7fce000-b7fd0000 rw-p b7fce000 00:00 0 
b7fd0000-b7fd1000 r--p 00000000 08:01 2698243    /usr/lib/locale/en_US.utf8/LC_TELEPHONE
b7fd1000-b7fd2000 r--p 00000000 08:01 2698244    /usr/lib/locale/en_US.utf8/LC_MEASUREMENT
b7fd2000-b7fd3000 r--p 00000000 08:01 2698245    /usr/lib/locale/en_US.utf8/LC_IDENTIFICATION
b7fd3000-b7fd8000 r-xp 00000000 08:01 2814670    /usr/lib/python2.5/lib-dynload/operator.so
b7fd8000-b7fd9000 rw-p 00005000 08:01 2814670    /usr/lib/python2.5/lib-dynload/operator.so
b7fd9000-b7fdc000 r-xp 00000000 08:01 2813880    /usr/lib/python2.5/lib-dynload/_locale.so
b7fdc000-b7fdd000 rw-p 00003000 08:01 2813880    /usr/lib/python2.5/lib-dynload/_locale.so
b7fdd000-b7fdf000 r-xp 00000000 08:01 671960     /usr/lib/skencil/Lib/intl.so
b7fdf000-b7fe0000 rw-p 00001000 08:01 671960     /usr/lib/skencil/Lib/intl.so
b7fe0000-b7fe2000 rw-p b7fe0000 00:00 0 
b7fe2000-b7ffb000 r-xp 00000000 08:01 556024     /lib/ld-2.5.so
b7ffb000-b7ffd000 rw-p 00019000 08:01 556024     /lib/ld-2.5.so
bfc96000-bfcb3000 rw-p bfc96000 00:00 0          [stack]
ffffe000-fffff000 r-xp 00000000 00:00 0          [vdso]
Aborted (core dumped)